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The Juniper Multicast Source Discovery Protocol (MSDP) router must be configured to only accept MSDP packets from known MSDP peers.


Overview

Finding ID Version Rule ID IA Controls Severity
V-254052 JUEX-RT-000800 SV-254052r844189_rule Medium
Description
MSDP peering with customer network routers presents additional risks to the DISN Core, whether from a rogue or misconfigured MSDP-enabled router. To guard against an attack from malicious MSDP traffic, the receive path or interface filter for all MSDP-enabled RP routers must be configured to only accept MSDP packets from known MSDP peers.
STIG Date
Juniper EX Series Switches Router Security Technical Implementation Guide 2024-06-10

Details

Check Text ( C-57504r844187_chk )
Review the router configuration to determine if there is a receive path or interface filter to only accept MSDP packets from known MSDP peers.

[edit firewall]
family inet {
filter {
term 1 {
from {
source-prefix-list {
msdp-peers;
}
protocol tcp;
destination-port msdp;
}
then accept;
}
term 2 {
from {
source-prefix-list {
msdp-peers;
}
protocol tcp;
source-port msdp;
}
then accept;
}

term default {
then {
syslog;
discard;
}
}
}
}
family inet6 {
filter {
term 1 {
from {
source-prefix-list {
msdp-peers-ipv6;
}
next-header tcp;
destination-port msdp;
}
then accept;
}
term 2 {
from {
source-prefix-list {
msdp-peers-ipv6;
}
next-header tcp;
source-port msdp;
}
then accept;
}

term default {
then {
syslog;
discard;
}
}
}
}

Note: Some platforms support the "port" keyword that filters on both source- and destination-port, which eliminates the need for separate terms. For instance:
filter {
term 1 {
from {
source-prefix-list {
;
}
[protocol|next-header] tcp;
port msdp;
}
then accept;
}

term default {
then {
syslog;
discard;
}
}
}

Verify the filter is applied to external interfaces or loopback.
[edit interfaces]
{
unit {
family inet {
filter {
input ;
}
address /;
}
family inet6 {
filter {
input ;
}
address /;
}
}
}
lo0 {
unit {
family inet {
filter {
input ;
}
address /32;
}
family inet6 {
filter {
input ;
}
address /128;
}
}
}
Note: Some Juniper devices support both monolithic filters and filter lists. Filter lists separate each term, or set of terms, into a separate filter that is applied sequentially to an interface. If using filter lists, the keywords "input" or "output" change to "input-list" or "output-list". Verify the final list item is a deny-all filter. The deny-all filter is created once per family and can be reused across multiple lists. For example:

input-list [ permit_mgt permit_routing_protocols default-deny ];

If the router is not configured to only accept MSDP packets from known MSDP peers, this is a finding.
Fix Text (F-57455r844188_fix)
Ensure the receive path or interface filter for all MSDP routers only accepts MSDP packets from known MSDP peers.

set firewall family inet filter term 1 from source-prefix-list msdp-peers
set firewall family inet filter term 1 from protocol tcp
set firewall family inet filter term 1 from destination-port msdp
set firewall family inet filter term 1 then accept
set firewall family inet filter term 2 from source-prefix-list msdp-peers
set firewall family inet filter term 2 from protocol tcp
set firewall family inet filter term 2 from source-port msdp
set firewall family inet filter term 2 then accept

set firewall family inet filter term default then syslog
set firewall family inet filter term default then discard

set firewall family inet6 filter term 1 from source-prefix-list msdp-peers-ipv6
set firewall family inet6 filter term 1 from next-header tcp
set firewall family inet6 filter term 1 from destination-port msdp
set firewall family inet6 filter term 1 then accept
set firewall family inet6 filter term 2 from source-prefix-list msdp-peers-ipv6
set firewall family inet6 filter term 2 from next-header tcp
set firewall family inet6 filter term 2 from source-port msdp
set firewall family inet6 filter term 2 then accept

set firewall family inet6 filter term default then syslog
set firewall family inet6 filter term default then discard

set interfaces unit family inet filter input
set interfaces unit family inet address /
set interfaces unit family inet6 filter input
set interfaces unit family inet6 address /

set interfaces lo0 unit family inet filter input
set interfaces lo0 unit family inet address /32
set interfaces lo0 unit family inet6 filter input
set interfaces lo0 unit family inet6 address /128